This is the 8344th most frequent Polish word.
pekinu
"Pekinu" in Polish refers to "Beijing," the capital city of China.
Here, 'Pekin' is used as a proper noun referring to Beijing, and the word 'pekinu' is in the locative case, indicating the location 'in Beijing'.
Kiedy byłem w Pekinie, jadłem tradycyjne chińskie potrawy.
When I was in Beijing, I ate traditional Chinese dishes.
In this sentence, 'Pekinu' is the genitive case of the noun 'Pekin', which indicates possession or relation, such as the location of Beijing on maps.
Mapy pokazują dokładną lokalizację Pekinu.
Maps show the exact location of Beijing.
Here, 'Pekinu' is again in the genitive case, showing a relationship or association—specifically the culture belonging to Beijing.